Sensors to determine use of heat with remote measuring are known - see for example German Patent No. 31 28 706 by the inventor hereof. According to this disclosure, a temperature sensor provides a frequency modulated measuring signal, representative of the temperature being sensed. The temperature sensor is located at the heat consumption or heat utilization position. The signals provide a group of pulses, which are pulse interval or space modulated. Transfer of the signals to an evaluation circuit is obtained over ordinary electric lines.
It is possible to connect a plurality of utilization points, and the sensors associated therewith, to a central evaluation unit in accordance with the teaching of the aforementioned patent. This is possible, however, only by transmission over electric lines. Electric lines, as known, are subject to external disturbances and noise influences. In large, complex installations, it is difficult to provide a clear and unambiguous association of temperature sensors, and terminals of a, or a plurality of evaluation units with respect to each other. Arrangements quickly become complex and difficult to maintain or repair.